1. Field of the Invention
The present invention relates generally to connecting devices and systems for gas lines, particularly electrically conductive (i.e., metallic) natural gas lines. More specifically, the devices and systems of the present invention are not only easy to use, reliable and inexpensive, but they also provide improved safety due to the use of non-conductive (relative to metal) material which impedes the unwanted flow of electricity along the gas line.
2. Discussion of the Prior Art
Gas lines in general are well known. For purposes of this specification, "gas line" is intended to mean any conduit, pipe or similar-type enclosed passageway used to transfer gas under pressure. Gas lines are commonly used to transport natural gas to residential or commercial buildings, where the gas is then ignited under controlled conditions to provide energy, generally for heating.
A main gas line generally lies underground and is linked to nearby buildings by supply lines which typically remain underground until just before reaching a building. The supply line is typically connected to a gas meter adjacent to where the line enters the building. From the meter the gas line may extend through various shut-off valves, regulators and other devices for consuming the natural gas.
Supply lines are typically fabricated from metal. Generally speaking, they readily conduct electricity. Hence, electric charge (due to gas flow or other changes in electrostatic potential along the gas line) will tend to quickly move along the gas line from areas of high electrical potential to lower electrical potential. Sources of electricity on the gas line include static charge, improper or defective wiring, lightning, and the like.
Gas lines are generally grounded, particularly where the metal line is buried in the ground, and therefore, any electricity along the supply line will tend to move toward ground. However such electrical conduction along the supply line can be problematic, even dangerous. It is particularly undesirable to allow gas lines to serve as a ground for discharging electrical current. This is because the discharge of electricity into the earth excites micro-organisms in the soil. The micro-organisms will attack the gas line, resulting in accelerated corrosion and premature failure.
Insulating fittings such as swivels and unions have been produced that can be included in gas lines to provide an insulated connection between pipes that carry combustible gas. These insulating fittings provide threaded connections in the manner of conventional pipe fittings. As a result providing an insulating connection requires considerable plumbing work to incorporate in the gas line. The amount of plumbing work is even greater when the insulated connection is positioned adjacent to a gas meter. This is because the insulating fitting must be incorporated between other pipe fittings that connect the gas line inside the building to the gas meter. This requires considerable effort to cut and thread the pipes, connect the fittings and the meter and finally to test all the connections for leaks. This requires a great deal of skilled labor, and the cost is significant.
A need therefore exists for a relatively inexpensive, reliable insulating coupling system for metal gas lines and gas meters, which is not only easy to use and install, but also avoids unwanted electrical conduction.